Moisture and temperature detection

ABSTRACT

Method and apparatus to continuously detect and measure the moisture level and/or temperature of a moving web of material. The web of material is run between a pair of vibrating members which rapidly move air back and forth through the web of material to bring the moisture content of the air into equilibrium with the moisture content of the fabric.

United States Patent Inventor Philip N. Smith Spartanburg, S.C.

Appl. No. 886,827

Filed Dec. 22, 1969 Patented July 27, 1971 Assignee Deering MillikenResearch Corporation Spartanburg, S.C.

MOISTURE AND TEMPERATURE DETECTION 10 Claims, 3 Drawing Figs.

US. Cl 73/73, 73/159 Int. Cl G0ln 5/02 Field of Search 73/73, 159,336.5. 338.6

[56] Reierences Cited UNITED STATES PATENTS 2,681,571 6/1954 Becker73/338.6 X 3,477,288 11/1969 Krcal et a1. 73/159 Primary ExaminerCarrollB. Dority, Jr. Attorneys-Norman C Armitage and H. William PetryABSTRACT: Method and apparatus to continuously detect and measure themoisture level and/or temperature of a moving web of material. The webof material is run between a pair of vibrating members which rapidlymove air back and forth through the web of material to bring themoisture content of the air into equilibrium with the moisture contentof the fabric.

PATENTEU JUL2 7 I97! DRYER SHEET 1 0F 2 FIG-2'" INVEN'J'UR. PHILIP N.SMITH M L W ATTORNEY MOISTURE REGAIN PATENTEUJULZTISTI 3595070 SHEET 2BF 2 85F l6 A QN V |O0F 70F I 2 85F "3" IOOF 0o TTON 5o so 70 so 90RELAT IVE HUMIDITY EQUIVALENT INVENTOR. PHILI P N. SMITH Emil/1WATTORNEY MOISTURE AND TEMPERATURE DETECTION In the processing of certainsheets of material such as paper, textile fabrics, etc., it is necessaryor desirable to measure the temperature and/or moisture content of thesheet during processing. This is especially true when one of the processsteps is drying wherein you want to maintain a certain moisture level inthe product being processed since a moisture content above or below acertain level indicates that the material is being under or over driedThis is particularly true in the processing of textile fabrics.Preferably, such measurement of moisture content and/or temperatureshould be continuous so that an operator can continuously check andreadjust the processing equipment to maintain substantially uniformconditions. Preferably, the desired uniform condi tions should be therelative humidity and/or temperature of the area wherein the webmaterial is to be further processed.

The percent moisture content of a given piece of textile material isdetermined primarily by the relative humidity of its environmental airand secondarily by its environmental temperature. It is customary tospeak of the moisture content as being that moisture content which ispresent under standard environmental conditions such as 70 F. and 65percent relative humidity.

Moreover, a plot or graph, such as that shown in FIG. 3, may be made ofthe moisture present in fabric or fibers under any specified conditionssuch as 40 percent, 50 percent or 60 percent relative humidity. Whensuch determinations have been made, such data may be plotted so that ifa piece of fabric has been conditioned (i.e., allowed to come intoequilibrium with its environmental surroundings), its moisture contentmay be derived from the graph by knowing the conditions of theenvironment, providing that sufficient time has elapsed for the materialto come into equilibrium.

In web drying operations, generally speaking it is desired to bring theweb out of the dryer at a moisture content such that the web neithergains nor loses moisture when brought into the surrounding conditions ofrelative humidity in the room. To dry more than this is a waste of heatand to dry less than this is to run the risk of mildew.

Normally, in conditioning fabric for test, the fabric is suspended topermit free air flow around the fabric in a room which is controlled asto relative humidity and temperature. This means that the fabric absorbsor loses moisture to bring it to equilibrium because of the unlimitedair flow available. Now if we surround the fabric with only a smallamount of air then the air will gain or lose moisture from or to thefabric, or we will be conditioning the air to the fabric. Since theabsolute weight of moisture present in the air is small in comparisonwith that in the fabric then this is accomplished with little change inthe fabric moisture.

Therefore, it is an object of the invention to accurately measure themoisture content of a continuously moving web of material.

Other objects and advantages will be clearly apparent as thespecification proceeds to describe the invention with reference to theaccompanying drawing in which:

FIG. l is a schematic representation of the new and novel moisturedetector:

FIG. 2 is a blownup cross-sectional view of the moisture detector perse; and

FIG. 3 shows a typical fabric moisture graph.

In the continuous processing of sheet material, it is usually necessaryto measure the moisture level in the material to ascertain whethercertain process steps are being properly controlled. In the preferredform of the invention shown in FIGS. l and 2, textile fabric is beingdried in dryer I2 and is taken up on a takeup roll 14. As discussedbriefly before, the invention is not restricted to textile fabric butcan be employed on such material as paper or on individual strandmaterial such as warp yarn from a warp beam. To accomplish the moisturedetection, a moisture detector, generally decimated I6 is locatedbetween the drver 1 2 and the takeun roll 14 with the fabric 10 passingbetween two opposed loud speakers 18 and 20 mounted on baffle plates 22,and 24, respectively.

The moisture present in a piece of material will come into equilibriumwith its environment, which is to say that apiece of fabric conditionedunder certain conditions and held in an area with a certain temperatureand humidity, will come into equilibrium with the surrounding air andthe air will come into equilibrium with the fabric. Logically, itfollows that the equilibrium condition can be reached much faster if thesurrounding air is moved back and forth through the fabric. The air,under such condition, rapidly picks up moisture from the fabric until itis in equilibrium therewith.

To accomplish the above result, the diaphragms 26 and 28 are connectedto a power source P to induce reciprocal movement of the movable coils30 and 3.2 to cause the diaphragms 26 and 28 to be vibrated out of phasewith one another to pump the air back and forth through the fabric 10,which pumping action rapidly brings the air and the fabric intoequilibrium. Mounted on one or the other of the loud speakers I8 or 20is a hygroscopic-transducer 34 which inresponse to the amount ofmoisture in the air changes the electrical resistance in the circuit ofthe meter 36 which is calibrated to read directly in percent relativehumidity.

The relative humidity reading can be used in many ways. Obviously, thisreading can be employed to merely check on the condition of the fabricat any desired time. Also, it can be employed to control the rate ofdrying of the drier in order to maintain certain preselected conditions.In processing a fabric, the fabric, after drying, can be eitherprocessed further or placed in storage. These further steps will takeplace in areas having a certain relative humidity and temperature. Ifthe measured relative humidity or temperature is below the relativehumidity of the area in which the further steps are taken then the drieris taking too much moisture out of the fabric since the fabric whenprocessed further will pick up moisture and come into equilibrium withthe surrounding atmosphere of the other area. 1 I

The preferred embodiment is directed to obtaining relative humiditymeasurements but obviously temperature measurements of the air can bealso taken in the same manner if it is desired to measure temperature.

The specific preferred detector 16 consists of the baffle plates 22 and24, which are approximately 3 feet square and mounted one-half inchapart, and the loud speakers 18 and 20, mounted to the baffles by suchmeans as screws 19, which have a frequency of vibration of the order of60 times per second. The loud speakers 18 and 20 are of the conventionalcommercially available type which have a movable coil 30 or 32 attachedto a diaphragm 26 or 28, a field magnet 38 or 40, a magnetic fieldwinding 42 or 44 and] a core 46 or 48.

The herein disclosed detector and! method of use provides for rapid andcontinuous measurement of a moving strand or strands of yarn andcontinuous lengths of material being processed. The close spacing of thebafiles 22 and 24 anduthe vibration frequency of the diaphragm allowsthe pumped air to come to equilibrium with the fabric very quickly sinceonly a small amount of moisture from the fabric is necessary. Although Ihave described in detail the preferred embodiment of the invention, itis contemplated that many changes may be made without departing from thescope or spirit of the invention and I desire to be limited only by theclaims.

That which I claim is:

l. A method of measuring a condition of a moving length of materialcomprising the steps of: providing a moving length of material, moving asmall amount of gaseous fluid backand forth through said length ofmaterial to bring said gaseous fluid in equilibrium with said materialand sensing and measuring a physical property of the gaseous fluid. u

2. The method of claim 1 wherein said gaseous fluid is air.

3. The method of claim 2 wherein said air is pumped back and forththrough said fabric. i

4. A method of measuring the moisture content of a moving length ofmaterial comprising the steps of: providing a moving length of material,moving a small amount of gaseous fluid back and forth through saidlength of material to bring said gaseous fluid in equilibrium with saidmaterial, sensing the moisture content of said gaseous fluid andmeasuring the humidity of the sensed moisture content.

5. The method of claim 4 wherein said gaseous fluid is air.

6. The method of claim 5 wherein said air is pumped back and forththrough said fabric.

7. A detector to measure a physical property of a length of materialcomprising: a pair of plates spaced from one another,

a first opening in one of said plates, a second opening in the cludes ahygroscopic transducer.

UNITED. STATES PATENT ()FFICE 5 CERTIFICATE OF CORRECTION Patent No.3,595,070 Dated 7, 1971 Invent0r(s) V Philip N., Smith It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column 4, line 5, "claim 3" should read claim 7 line 8, "claim 3" shouldread claim 8 line 9, "diaphragm" should read diaphragms line 10, "claim5" should read claim 9 Signed and sealed this 29th day of February l972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents FORM FO-l05O (10-59) USCOMM-DC 0O376-F69 Q U 5 GO ERNMENTPRINTING OFFICE 19.9 O35833l

1. A method of measuring a condition of a moving length of materialcomprising the steps of: providing a moving length of material, moving asmall amount of gaseous fluid back and forth through said length ofmaterial to bring said gaseous fluid in equilibrium with said materialand sensing and measuring a physical property of the gaseous fluid. 2.The method of claim 1 wherein said gaseous fluid is air.
 3. The methodof claim 2 wherein said air is pumped back and forth through saidfabric.
 4. A method of measuring the moisture content of a moving lengthof material comprising the steps of: providing a moving length ofmaterial, moving a small amount of gaseous fluid back and forth throughsaid length of material to bring said gaseous fluid in equilibrium withsaid material, sensing the moisture content of said gaseous fluid andmeasuring the humidity of the sensed moisture content.
 5. The method ofclaim 4 wherein said gaseous fluid is air.
 6. The method of claim 5wherein said air is pumped back and forth through said fabric.
 7. Adetector to measure a physical property of a length of materialcomprising: a pair of plates spaced from one another, a first opening inone of said plates, a second opening in the other of said platesopposite to said first opening, means to pump air operably associatedwith said plates to pump air back and forth through said openings and asensing means in the path of travel of said air.
 8. The structure ofclaim 3 wherein said pumping means includes a first vibrating diaphragmover said first opening and a second vibrating diaphragm over saidsecond opening.
 9. The structure of claim 3 wherein means are providedto vibrate said diaphragm out of phase with one another.
 10. Thestructure of claim 5 wherein said sensing means includes a hygroscopictransducer.